SO my son is now 7 and has grown too big for the two vehicles I modded.
The good news is my daughter is 4 and now the perfect age! So I intend further modifications to the firetruck and police car.

Let's focus on the question at hand. Speed. So I modded by dodge charger police car from stock to 18volts. Ran great, no problems. I then modded again from 18volts to 24.
Problems. I am not sure yet what the issue is but the current situation is this:

I am running 24volts (2 12volt in series) into the shifter and then directly into (2) Titan 775 Traxxas

I have a separate 12volt SLA to power everything else. (lights, siren, etc...)

Normal speed works, reverse works, but high gear only fires one of the motors and not the other. I don't know why. I reversed the motors (left to right), tried again, and the motor that wasn't working now is. So I have ruled out that there is a problem with the motors themselves. I don't know what is causing only one motor to fire in high gear and not the other.

I am hoping 12vwiz is still active on this board. I used his diagram initially to mod to 18volts with no problems. Now I don't see why increasing voltage and using the same schematic would produce a different result.

The diagram from 12vwiz was ok to use to mod to 18v but running 24v through the stock shifter and pedal switches will cause them to fail. Most 24v upgrades include relays to take the higher current loads off the switches. Also, your motors may be ok at 24v but the gearboxes will not like direct 24v so a 24v upgrade also usually includes an ESC for softer starts.

Last edited by Rob222 on Sat Dec 26, 2015 2:13 pm, edited 1 time in total.

Hello,..I just modafied my kid trax dodge charger up to 24Volts an it's faster than ever. If any one wants to contact me an want to know more on how to do this please message for more details...thank you.

Cheetos - How did you do it and bypass board? I just got a mini Cooper S and want to go to 18v or 24v but trying to find easiest way to do it! I know there are many diagrams but I am challenged to understand them!!
Thanks